Turntable drive



June 6, 1939. I ERWQQD 2,161,148

TURNTABLE DRIVE Filed Feb. 20, 1939 "1 moved from a platform forming part of a cabinet Patented June 6, 1939 UNITED STATES- TURNTABLE nmvE Joseph Erwood, Chicago, Ill., assignor to The ,Webster Company, Chicago, 111., a corporation of Illinois Application February 20,1939, Serial No. 257,315

5 'Claims.

The following invention, which relates to a turntable drive for phonographs and the like, is concerned with certain improvements by which a simple yet effective frictional drive is maintained between a motor which depends from a supporting base and a turntable mounted to rotate above the base, the entire mechanism being unitary in character so that it may be applied to or reor otherwise. More particularly the present 'mechanism comprises a horizontal off center pivotal mounting for a motor which is suspended below the base with its vertically disposed operating shaft extended upwardly through an opening therein, the shaft swinging with the motor so as to occupy various positions relative to the base and to a floating idler wheel which is movably supported thereon for receiving frictional driving engagement from a roller which may be carried upon the shaft near its upper end; or simply a floating idler wheel interposed in the transmission between a roller on the motor shaft and a circular flange depending from the turntable, the wheel diameterbeing intermediate that of the roller and flange so that a greater contact area is afforded between the wheel and flange than would be the case if the frictional drive were directly between the roller and flange, the movable mounting of the wheel being'such that when advanced toward either the roller or flange it engages with the other with a like variable pressure.

The idler wheel, according to the present mechanism, is mounted above the turntable in a position to engage with the inner face of a peripheral flange depending therefrom. The relationship of the various components of the drive is such that I may utilize a gravity force which tends to swing the motor upon its horizontal axis so that the driving roller aflixed to its shaft near the upper end engages with pressure against the idler wheel which is thereby held with pressure against the turntable flange so that a satisfactory frictional driving connection is maintained at all times, extending from the motor below the base to theturntable thereabove'.

The mechanism herein described is simple and dependable, it is easily assembled and operated, and it permits of ready exchange of driving rollers .of. varying sizes, so that a constant speed of operation for the turntable may be assured if a synchronous electric motor be used on alternating currents of different cycles.

These and other objects as will hereinafter appear may be realized from a construction, of which a suggestive embodiment is set forth in the accompanying drawing in the manner folbase plate. raised sufficiently to position the idler wheel up idler wheel and driving roller, the former movably mounted on abase plate of which a large portion also appears in elevation;

Fig. 2 is a vertical-section on an enlarged scale Fig. 6 is a fragmentary plan view of a turntable partly broken awayto exhibit therebelow a modified transmission which proceeds from a motor having a fixed mounting.

The turntable operating mechanism is unitary in character in that it is all mounted upon a base plate B adapted to be rested upon and secured to the platform P of'a cabinet or other support, as is customary. The base plate occupies a position over an'opening o in the platform and is itself provided with .a relatively small aperture a which may, if desired, be elongated in form.

Extending upwardly from the base plate is a post p over which may be fitted the hub h of a turntable T of sheet metal or the like. This post ,aifords a fixed mounting in that its axis remains stationary, and, when positioned thereupon, the turntable is adapted to revolve freely aboutthe post. diameter to fit within the central opening of an ordinary disk record D when positioned upon the turntable in the conventional way.

According to Figs. 1 to 5, the turntable is provided with a depending peripheral flange f. In engagement with the inner face of this flange is a friction tread t, preferably a band of rubber or the like, which is fitted peripherally about an idler wheel W which is mounted to revolve about a stud s which is carried near the swinging end of an arm A pivotally mounted as at 6 upon the The swinging end of this arm is close to the turntable so as to be normally concealed from view.

From the base plate which is desirably of sheet metal is struck a pairv of bracket arms b which depend below the platform for an appreciable distance. Each arm near its lower end is apertured to receive a bushing 1 formed therethrough with an axial opening. 8 to receive a trunnion 9, two

such trunnions being extended outwardly, one

from each end wall ID of a saddle II. The trunnions, as best shown in Fig. 5,'are formed adja- "cent one vertical edge of the saddle so as to occupy an off-center position relative thereto. When supported between the two bracket arms, the sad- In its upper region a the post is of reduced die is free to swing within the bushings which furnish mountings therefor.

Carriedfupon the saddle is a motor M, desirably a synchronous electric motor, whose field II is connected to the saddle as by spaced bolts #5 which support at their upper ends a cross bar I 6. Upon the under sideof the saddle is secured a strap H, a similar strap l8 being amxed to the upper side of the cross bar. A shaft S which is connected to the armature IQ of the motor extends vertically from a thrust bearing in the lower strap ll through a second bearing 2| in the upper strap l8 and thence through the aperture a in the base plate to terminate adjacent the under side of the turntable where I have aflixed a driving roller 22 which lies adjacent the tread of the idler wh'eel. Fitted around the periphery of the roller I have shown a friction tread 'band 23 of rubber or other appropriate material.

By reference to Fig. 2 it will be observed that the motor, which is of generally symmetrical form, is pivotally supported ofi-oenter so that its shaft and preponderance of weight lies to the side of the saddle which is toward the idler wheel.- By reason of this fact the motor tends to swing upon its pivotal support in a direction which will advance its driving roller 22 against the idler wheel which, in consequence, may be swung upon its pivotal mounting toward the inner face of the turntable flange. 1 I accordingly utilize gravity Jorce, obtainable by the off-center mounting of thFmotol. (1) to advance the driving roller against the idler..wheel and (2) to advance the idler wheelagainst the-turntable flange.

If the turntable be removed from its pivot post there is no longer any restraint to swinging movement of the motor which is free to tilt as far as permitted by the confines of the aperture a through which the shaft is extended. This aperture need not be very large-just long enough to afford to the shaft a'range of movement which will assure an effective engagement with the idler wheel under operating conditions. With the shaft swung over against one edge of the aperture which serves as a stop therefor the idler wheel is also swung around a corresponding distance, this movement requiring the pivoted arm to swing about its pivot point 6. The parts are therefore displaced from their normal operating positions but very little when the turntable is removed. Upon replacing the turntable, the depending flange thereof is brought against the tread of the idler wheel, after which the turntable is moved over to the required position for fitting upon its pivot post. In reaching this position, the idler wheel moves with the turntable flange with the result that the shaft is finally brought back'to its normal operating position which, as shown in Fig.2, is substantially vertical.

Experience has proven that a small diameter driving roller, when engaged with the concave face of a large diameter peripheral flange of a turntable, will not establish a satisfactory frictional transmission therefor. This is due in large part to the small area of the contact surface between theroller and the flange, consequent upon the wide difference in diameter of these parts oi! the tran mission. The present transmission affords a m ch more efiective contact between the driving rbller and the idler wheel on account of the frictional properties of their engaging surfaces, and between the idler wheel and the turntable flange, due to the reduced differences in the diameters of their interengaging surfaces.

As shown, the driving roller is removably affixed to the motor shaft. This is desirable because it permits the ready substitution of another roller of different size. If the motor be a synchronous electric motor designed to operate on a 50 cycle alternating current, the driving roller should be of a different size than in the case of a motor which is designed to operate upon a 60 cycle current, if the speed of turntable rotation is to remainthe same. By the simple expedient of using a. driving roller of proper size, the correct turntable speed may be assured.

It will be noted that the base plate carries all the parts of the present operating mechanism,

being provided on its upper face with a fixed mounting for the turntable and with a movable mounting for the idler wheel, and on its under 1' ace with a support wherein the motor is pivotally mounted in an off-center position so as to utilize the force of gravity for swinging itself and the upper shaft end against the idler wheel which,

in turn, is pressed against the turntableflange.

of swinging movements, yet small enough to limit this swinging movement to a short distance. The opening in the platform is somewhat less in size than is the base plate, so that the edges of the latter may rest upon the platform for securement thereto, but permitting the base plate, when disengaged therefrom, to beiifted together with the motor supported therebelow, the motor then passing through such opening in the platform without interference therefrom. All these factors contribute to ease and simplicity in the assembly and care of the present mechanism which has been found by experience to provide a very satisfactory transmission adapted to accommodate itself to possible irregularities in the turntable flange or even to slight differences in the diameters' of such flanges.

In Fig. 6 I have shown a modification of the transmission which is adapted to be used with a motor having a fixed mounting. In this case the roller 22 at the upper end of the shaft rotates in a fixed position; consequently any variation in frictional pressure between the roller and idler wheel W must result from movement of the latter alone. This I accomplish by mounting the roller on an arm A one end of which is rested on the base plate B and provided with a slot 25 through which is entered a securing pin or rivet 6. The wheel so mounted is free to swing upon the pin as a pivot, and also to slide within the limits of the slot wherein this pin is entered. The wheel diameter is such that it occupies a position between the roller and the flange f of the turntable T so as to transmit motion from one to the other.

In order that the wheel may bear with pressure against both the roller and the turntable flange, I provide a light spring such as the tension leaf 26 having a fixed mounting upon a lug 21 which upstands from the base plate, the free end of the leaf bearing with pressure against the arm A which supports the wheel. By this. means there is maintained a constant pressure of the wheel against both the roller and the turntable flange such that a necessary degree of friction is maintained for the transmission of motion from the motor to the turntable.

In the construction last described the advantages of a floating idler wheel are retained. In

the case of irregularities in the turntable flange,

or of a slight bend in the motor shaft, the idlerwheel may shift its position slightly, as required for accommodation of itself between these two elements in the transmission system. Also, in the case of turntables whose flanges may vary slightly in diameter, theidler wheel is enabled to adjust itself, under tension of thespring 26, so as to establish a satisfactory driving connection from the motor. In accomplishing this, a greater area of surface contact is afforded at the points of frictional connection with the turntable, due to the use of an intermediate idler wheel of substantial diameter,- than would be the case if the drive proceeded directly from the roller to the turntable flange.

I claim:

1. In a phonograph, the combination of an apertured base plate aifording upon its upper side two mountings, one fixed and the other movable, a turntable provided with a depending flange adapted for rotatable fitting upon the fixed mounting and an idler wheel adapted for peripheral driving engagement with the turntable flange supported on the movable mounting, a fixed support depending from the base plate, a motor having an ofl-center horizontal pivotal mounting on the support, a shaft extended upwardly from the motor through the base plate aperture, and a roller carried by the shaft near its upper end adapted to frictionally engage the idler wheel, the preponderance of motor weight lying to the side of the axis of its pivotal mounting whichis of the motor shaft tends by gravity to bear with pressure against the idler wheel and to hold the idler wheel with pressure against the turntable flange to maintain a drivingconnection therebetween.

2. In a phonograph, the combination of an 5 apertured base plate of sheet metal, a fixed mounting extending upwardly from the base plate, a swinging moimting extending upwardly from the baseplate, two arms struck from the base plate and depended therebelow in spaced 0 relation, a saddle pivotally supported between the two arms, a motor carried on the saddle with preponderance of its weight lying to the side of the pivotal axis of the saddle which is toward the pivotal mounting above the base plate, a turn- 55 table having a depending flange adapted to be fitted rotatably upon the fixed mounting extending above the base plate, an idler wheel carried near the free end of the swinging mounting on the base plate adapted for peripheral engagement .0 with the turntable flange, a shaft extended upwardly from the motor through the aperture of the base plate, and a driving roller carried by the shaft near its upper end in a position adapted to engage the idler wheel, the off-center mounting t of the motor causing the upper shaft end'to 7 two mountings, one fixed and the other movable,

a turntable provided with a depending flange adapted for rotatable fitting upon the fixed mounting and an idler wheel adapted for peripheral driving engagement withthe turntable flange supported'on the movable mounting, a ll pair of arms struck from the base plate and downwardly extended therefrom in spaced relation, a motor having a mounting below the base plate between the two arms, a shaft extended upwardly from the motor through the base plate 10 aperture, and a roller carried by the shaft near its upper end adapted to frictionally engage the idler wheel, the motor mounting between the depending arms below the base plate being movable.

to permit the upper end of its shaft, and the driv- 15 ing roller thereon, to advance toward the idler wheel and to press the latter against the turntable flange whereby to maintain a frictional driving connection therebetween.

4. In a phonograph, the combination of a plat- 20 form through which is an opening, and a motor turntable unit comprising an apertured base plate mounted on the platform over the opening, a shaft extending vertically through the base plate aperture, a roller affixed to the shaft near its 25 upper end, an arm pivoted to the base plate adapted to swing thereon in a horizontal plane, an idler wheel rotatably carried by the arm adapted to receive peripheral engagement from the shaft roller and to be driven thereby, a post so upstanding from the base plate, a turntable rotatably mounted on the post and formed with a depending flange adapted to receive peripheral engagement from the idler wheel, a motor .hav-

ing a rotor in operative connection with the shaft 35 positionedbelow the base plate, and means depending from the base plate affording a pivotal support for the motor at a point ofl center and away from the idler wheel axis whereby the motor tends by gravity to force to -swing about a horizontal axis in a direction'whicli normally holds the shaft roller against the idler wheel and the latter against the turntable flange to maintain a driving connection therebetween.

5. In .a phonograph, the combination of an 5 apertured base plate affording upon its upper side two mountings one being movable, an idler wheel floatingly supported on the mov'ablemounting, a turntable fitting upon the other mounting and provided with a depending flange adapted to be frictionally engaged by the idler wheel, a motor carried by the base plate and supported from a point therebelow, a shaft extended through, the base plate aperture to a,point adjacent the idler wheel, a driving roller carried by u the shaft near the upper end thereof adapted for engagement with the periphery of the idler wheel,

the idler wheel affording a floating transmission element between the driving roller and the tumtable flange, and means comprising the support for the idler wheel operating to maintain a yieldable pressure contact between the idler wheel and the driving roller and to hold the idler wheel with pressure against the turntable flange and cooperating with the movable mounting of the u idler wheel to maintain during rotation of the turntable floating action of the idler wheel with relation to the flange of the turntable as may be required by irregularities in the turntable flange and to accommodate turntables having flanges 7o varying slightly in diameter.

. JOSEPH ERWOOD. 

